Wireless power transferring method and device therefor

ABSTRACT

According to an embodiment of the present invention, a method for transferring wireless power by an electric power transmitter may comprise: a selection step of monitoring a placement or a removal of an object on or from an interface surface of the power transmitter; a ping step of performing a digital ping and receiving a response from a power receiver; an identifying/configuring step of receiving a configuration packet including configuration information of the power receiver; and a negotiating step of transmitting a capability packet including information on a level of power transferred by the power transmitter, wherein the capability packet may include an NFC detection field indicating whether the power transmitter has a capability of detecting an RFID and/or an NFC, and/or whether the RDID and/or the NFC is detected.

TECHNICAL FIELD

The present invention relates to a wireless power transferring methodand a device therefor.

BACKGROUND ART

A contactless wireless charging method is an energy transfer method forelectromagnetically transferring energy without using a wire in a methodfor transmitting energy through an existing wire so that the energy isused as power for an electronic device. The contactless wirelesstransmission method includes an electromagnetic induction method and aresonant method. In the electromagnetic induction method, a powertransmission unit generates a magnetic field through a powertransmission coil (i.e., a primary coil), and a power reception coil(i.e., a secondary coil) is placed at the location where an electriccurrent may be induced so that power is transferred. In the resonantmethod, energy is transmitted using a resonant phenomenon between thetransmission coil and the reception coil. In this case, a system isconfigured so that the primary coil and the secondary coil have the sameresonant frequency, and resonant mode energy coupling between thetransmission and reception coils is used.

DISCLOSURE Technical Problem

When a Radio Frequency Identification (RFID) card or a Near FieldCommunication (NFC) card is placed between a power transmitter (e.g.,wireless charger) and a power receiver (e.g., mobile device, etc.), apower transmitter without having RFID/NFC detection function cannotdetect an RFID/NFC card. In addition, even with the FOD method definedby WPC, which is a standard for a wireless power transmission/receptionsystem, the power transceiver cannot detect the RFID/NFC card. Thereason is that the FOD method defined in the WPC is defined to detectforeign object based on how much power transmitted from the powertransmitter to the power receiver is lost (e.g., if the transmissionefficiency is below a pre-configured level), but in the case of anRFID/NFC card, even if it is placed between the power transmitter andthe power receiver, power loss does not occur. Furthermore, since theoperating frequency (e.g., about 100 to 205 kHz) of the electric powertransceiver defined in the WPC is different from the operating frequencyof the RFID/NFC card (e.g., about 13.56 MHz), even with the frequency itis difficult to detect the RFID/NFC card.

If the wireless power transceiver fails to detect the presence of theRFID/NFC card and maintains the power transmission, there exists theproblem that the RFID/NFC card continuously exposed to a strong magneticfield may eventually be damaged and causes financial/property damage toa user. Furthermore, stability problems due to the heat generation ofthe RFID/NFC card can be raised.

Therefore, in the present specification, a method for detecting such anRFID/NFC card will be proposed. The description of the embodimentsproposed herein can be cooperated with the WPC Qi wireless powertransmission system power class 0 specification Version 1.2.3 andVersion 1.3.

Technical Solution

According to the present invention, a method for transferring wirelesspower by a power transmitter, the method comprises: a selection step ofmonitoring a placement or a removal of an object on or from an interfacesurface of the power transmitter; a ping step of performing a digitalping and receiving a response from a power receiver; anidentifying/configuring step of receiving a configuration packetincluding configuration information of the power receiver; and anegotiating step of transmitting a capability packet includinginformation on a level of power transferred by the power transmitter,wherein the capability packet may include an NFC detection fieldindicating whether the power transmitter has a capability of detectingan Radio-Frequency Identification (RFID) and/or an Near FieldCommunication (NFC), and/or whether the RFID and/or the NFC is detected,and when the NFC detection field indicates that the power transmitterdoes not have the capability of detecting the RFID and/or the NFC, themethod further comprising steps of: receiving a first End Power Transfer(EPT) packet for indicating a termination of a power transfer from thepower receiver; wherein the first EPT packet includes a first EPT coderequesting a removal of a power signal for a pre-configured time,removing the power signal for the pre-configured time, and returning tothe ping step.

Further, the NFC detection field may be divided into a first subfieldindicating whether the power transmitter has the capability of detectingthe RFID and/or the NFC, and a second subfield indicating whether theRFID and/or the NFC is detected.

Further, the method for transferring wireless power may comprises a stepof further comprising a step of receiving a second EPT packet from thepower receiver, when re-performing the digital ping according to thereturning to the ping step, wherein the second EPT packet may include asecond EPT code requesting the removal of the power signal as the RFIDand/or the NFC is detected by the power receiver for the pre-configuredtime.

Further, the method for transferring wireless power may furthercomprises a step of removing the power signal, and providing a detectionresult of the RFID and/or the NFC to a user when the second EPT packetis received.

Further, the method for transferring wireless power may furthercomprises steps of a calibration step of adjusting a specific parameterto improve the foreign object detection capability during the powertransfer of the power transmitter, when the NFC detection fieldindicates that the power transmitter has the capability of detecting theRFID and/or the NFC, and the RFID and/or the NFC is not detected, and astep of not entering the calibration step, when the NFC detection fieldindicates that the power transmitter has the capability of detecting theRFID and/or the NFC, and the RFID and/or NFC is detected.

Further, the step of not entering the calibration step may furthercomprises the step of removing the power signal and providing adetection result of the RFID and/or the NFC detection to a user.

Further, the pre-configured time may be indicated via a packettransmitted from the power receiver in the negotiating step.

Further, the packet may include a field indicating the time at which thepower transmitter removes the electric power signal.

Further, the field may indicate the power transmitter to immediatelyremove the power signal or to remove the power signal when the powertransmitter receives the first EPT packet.

Further, the packet may indicate the pre-configured time in units of 0.2seconds.

Further, the capability packet may be transmitted as a response to ageneral request field transmitted from the power receiver.

Further, a power transmitter according to another invention comprises acoil assembly comprising at least one primary coil to generate amagnetic field; a power conversion unit configured to convert electricenergy into a power signal; and a communication and control unitconfigured to control a communication with a power receiver and a powertransfer, wherein the communication and control unit is furtherconfigured to: monitor a placement or a removal of an object on or froman interface surface of the power transmitter; perform a digital pingand receive a response from the power receiver; receive a configurationpacket including configuration information of the power receiver; andtransmit a capability packet including information on a level of powertransferred by the power transmitter, wherein the capability packet mayinclude an NFC detection field indicating whether the power transmitterhas a capability of detecting an Radio-Frequency Identification (RFID)and/or an Near Field Communication (NFC), and/or whether the RFID and/orthe NFC is detected, and when the NFC detection field indicates to thepower transmitter that there is no ability to detect the RFID and/or theNFC, the communication and control unit may receive a first End PowerTransfer (EPT) packet for indicating a termination of the power transferfrom the power receiver, wherein the first EPT packet includes a firstEPT code requesting a removal of a power signal for a pre-configuredtime, and remove the power signal for the pre-configured time, andre-performing the digital ping.

Further, the NFC detection field may be divided into a first subfieldindicating whether the power transmitter has the capability of detectingthe RFID and/or the NFC, and a second subfield indicating whether theRFID and/or the NFC is detected.

Further, a power receiver according to another invention comprises, acoil assembly including at least one secondary coil to receive power; apower pick-up unit configured to convert a power signal received throughthe coil assembly into electric energy; an NFC functional unitconfigured to detect Radio Frequency Identification (RFID) and/or NearField Communication (NFC); and a communication and control unitconfigured to control a communication with the power transmitter and apower transfer; wherein the communication and control unit furtherconfigured to: transmit a response for a digital ping of the powertransmitter; transmit a configuration packet including configurationinformation of the power receiver; and receive a capability packetincluding information on a level of power transferred by the powertransmitter, wherein the capability packet may include an NFC detectionfield indicating whether the power transmitter has a capability ofdetecting an Radio-Frequency Identification (RFID) and/or an Near FieldCommunication (NFC), and/or whether the RFID and/or the NFC is detected,and when the NFC detection field indicates to the power transmitter thatthere is no ability to detect the RFID and/or the NFC, the communicationand control unit may transmit a first End Power Transfer (EPT) packetfor indicating a termination of a power transfer from the powerreceiver; wherein the first EPT packet includes a first EPT coderequesting a removal of a power signal for a pre-configured time, anddetect the RFID and/or the NFC using the NFC functional unit for thepre-configured time.

Further, the NFC detection field may be divided into a first subfieldindicating whether the power transmitter has the capability of detectingthe RFID and/or the NFC, and a second subfield indicating whether theRFID and/or the NFC is detected.

Advantageous Effects

According to an embodiment of the present invention, an RFID/NFC(card/tag) can be efficiently detected while maintaining compatibilitywith the wireless power charging protocol defined in the WPC standard,and thus it has the effect of preventing damage to the RFID/NFC(card/tag) of a user and solving the safety problem that may occur dueto the heat generation of the RFID/NFC (card/tag).

In addition, various effects according to the embodiment of the presentinvention will be described below in detail.

DESCRIPTION OF DRAWINGS

FIG. 1 illustrates an embodiment of various electronic devices intowhich a wireless charging system is introduced.

FIG. 2 illustrates a wireless power transmission/reception systemaccording to an embodiment of the present invention.

FIG. 3 is a block diagram illustrating a power transmission/receptionmethod in an inductive mode.

FIG. 4 illustrates a power transmission control method in the inductivemode.

FIG. 5 illustrates a power transmission device according to anembodiment of the present invention.

FIG. 6 illustrates a power reception device according to an embodimentof the present invention.

FIG. 7 illustrates a frame structure for data communication during powertransmission.

FIG. 8 is a diagram illustrating a sync packet according to anembodiment of the present invention.

FIG. 9 is a diagram illustrating a power transmission method in a sharedmode.

FIG. 10 is a diagram illustrating a method for controlling a wirelesspower transmission/reception system to which FOD extension is appliedaccording to an embodiment of the present invention.

FIG. 11 illustrates an EPT packet format defined in the current WPCstandard.

FIG. 12 illustrates a capability packet format according to a firstembodiment of the present invention.

FIG. 13 is a table illustrating a next operation of a power receiverreceiving an NFC detection/protection bit/field according to anembodiment of the present invention.

FIG. 14 illustrates a capability packet format according to a secondembodiment of the present invention.

FIG. 15 is a table illustrating the next operation of a power receiverthat has received NFCPP and NFCD bits/fields according to an embodimentof the present invention.

FIG. 16 illustrates a capability packet format according to a thirdembodiment of the present invention.

FIG. 17 illustrates an RFID/NFC detection method of a power receiveraccording to the first embodiment of the present invention.

FIG. 18 is a flowchart showing the embodiment of FIG. 17 in terms ofoperation of a power transmitter and a power receiver.

FIG. 19 illustrates an RFID/NFC detection method of a power receiveraccording to a second embodiment of the present invention.

FIG. 20 is a flowchart showing the embodiment of FIG. 19 in terms ofoperation of a power transmitter and a power receiver.

FIG. 21 illustrates an RFID/NFC detection method of a power receiveraccording to a third embodiment of the present invention.

FIG. 22 is a flowchart showing the embodiment of FIG. 21 in terms ofoperation of a power transmitter and a power receiver.

FIG. 23 illustrates a re-ping time packet format according to anembodiment of the present invention.

FIG. 24 illustrates a configuration packet format according to anembodiment of the present invention.

FIG. 25 illustrates a specific request packet format according to anembodiment of the present invention.

FIG. 26 is a flowchart illustrating a power transfer method of a powertransmitter according to an embodiment of the present invention.

BEST MODE FOR INVENTION

Terms used in this specification are common terms which are now widelyused by taking into consideration functions in this specification, butthe terms may be changed depending on an intention of those skilled inthe art, a use practice, or the appearance of a new technology.Furthermore, in a specific case, some terms have been randomly selectedby the applicant. In this case, the meaning of a corresponding term isdescribed in a corresponding part of a corresponding embodiment.Accordingly, the terms used in this specification should not beunderstood simply based on their names but should be understood based ontheir substantial meanings and contents over this specification.

Furthermore, although embodiments of the present invention are describedin detail with reference to the accompanying drawings and contentsdescribed in the drawings, the present invention is not limited to orrestricted by the embodiments.

Hereinafter, some embodiments of the present invention are described indetail with reference to the accompanying drawings.

FIG. 1 illustrates an embodiment of various electronic devices intowhich a wireless charging system is introduced. In FIG. 1, electronicdevices are classified according to an amount of power transmitted andreceived in the wireless charging system.

Low power (approximately 5 W or less or approximately 20 W or less)wireless charging may be applied to wearable devices such as a smartclock and smart glass and mobile/portable electronic devices such as anearphone, a remote controller, a smart phone, PDA, a tablet PC, etc.Medium power (approximately 50 W or less or approximately 200 W or less)may be applied to medium and small appliances such as notebookcomputers, robot cleaners, TVs, sound devices, cleaners, monitors, andthe like. In addition, large power (approximately 2 kW or less or 22 kWor less) wireless charging may be applied to kitchen appliances such asa blender, a microwave oven, and an electric rice cooker, personalmobile devices such as a wheelchair, an electric kickboard, an electricbicycle, and an electronic device/moving means such as an electricvehicle, etc. The electronic devices/moving means illustrated in FIG. 1may include a power receiver to be described below.

Hereinafter, a low power and a mobile device will be mainly described,but this relates to an embodiment, and the wireless powertransmission/reception method according to the present invention may beapplied to various electronic devices described above.

Wireless Power Consortium (WPC) standardizes wireless powertransmission/reception related technology for standardization ofwireless power transmission/reception devices.

The recently developed wireless charging system may support low powertransmission and reception up to approximately 5 W. However, recently, asize of a mobile device becomes large and a battery capacity alsoincreases, in the case of such a low power charging system, there is aproblem in that a charging time is long and efficiency is lowered, andas a result, a wireless charging system for supporting medium powertransmission and reception of up to approximately 15 W to 20 W. At thesame time, a wireless charging system having a resonance method added tocharge a plurality of electronic devices has also been developed. Thepresent invention relates to a wireless charging system having aresonance method added and intends to propose a resonance type wirelesscharging transmitter/receiver that is compatible with alow-power/medium-power induction-type wireless chargingtransmitter/receiver.

Hereinafter, the inductive and resonant wireless charging transmitterand wireless charging receiver proposed by the present invention and acharging method and a communication protocol using the same will bedescribed. Further, hereinafter, a resonance type/mode may be referredto as a shard type/mode. In addition, hereinafter, the wireless powertransmitter may be referred to as a power transmitter or transmitter andthe wireless power receiver may be referred to as a power receiver orreceiver.

FIG. 2 illustrates a wireless power transmission/reception systemaccording to an embodiment of the present invention.

In FIG. 2, the wireless power transmission/reception system includes amobile device and a base station that receive power wirelessly.

The mobile device includes a power receiver that receives wireless powerthrough a secondary coil and a load that receives and stores the powerreceived by the power receiver and supplies the received and storedpower to a device. In addition, the power receiver may include a powerpick-up unit that receives a wireless electric power signalcommunication and converts the received wireless electric power signalinto electric energy through the secondary coil and a communications andcontrol unit that controls communication and electric power signaltransmission/reception (power transfer/reception) with the powertransmitter. The mobile device may also be referred to below as a powerreception device.

The base station as an apparatus that provides inductive power orresonant power may include one or more power transmitters and systemunits. The power transmitter may transmit the inductive/resonant powerand control power transmission. The power transmitter may include apower conversion unit that generates a magnetic field through a primarycoil(s) and converts/transmits the electric energy into an electricpower signal and a communications and control unit that controlscommunication and power transfer with the power receiver so as totransmit the power at an appropriate level. The system unit may performother operation controls such as input power provisioning, control of aplurality of power transmitters, and user interface control. The basestation may also be referred to below as a power transmission device.

The power transmitter may control transmission power by controlling anoperating point. The controlled operating point may correspond to acombination of a frequency, a duty cycle, and a voltage amplitude. Thepower transmitter may control the transmitted power by adjusting atleast one of the frequency, the duty cycle/duty ratio, and an amplitudeof input voltage. Further, the power transmitter may supply constantpower and the power receiver may control the received power bycontrolling a resonant frequency.

A coil or coil portion may hereinafter be referred to as a coilassembly, a coil cell, or a cell, including the coil and at least oneelement adjacent to the coil.

Inductive Mode—Low Power and Mid Power

Hereinafter, a power transfer method of the power transmitter/receiveroperating in the inductive mode will be described first. However, atleast one of a method for describing the inductive mode or phasesincluded in the method may be used selectively or optionally in theresonant mode.

FIG. 3 is a block diagram illustrating a power transmission/receptionmethod in an inductive mode.

In the wireless charging system according to the present invention, thewireless charging may be performed through five phases. The five phasesmay include a selection phase, a ping phase, an identification andconfiguration phase, a negotiation phase, and a power transfer phase andhowever, the negotiation phase may be omitted in the low power-modepower transmission/reception. That is, in the lower power mode, thepower transmission/reception may be performed by four phases and in theintermediate power mode, the negotiation phase may be additionallyperformed.

In the selection phase, the power transmitter monitors contact/departureof an object with respect to an interface surface provided in thetransmitter. As shown in FIG. 2, the wireless power transmitter maysense the contact of an external object by applying the electric powersignal. In other words, the power transmitter applies a short electricpower signal to the primary coil and senses the current of the primarycoil generated by the electric power signal to monitor the presence ofthe external object. In addition, when the power transmitter receivessignal strength information (packet) monitored in the selection phaseand detects the object based on the received signal strength information(packet), the power transmitter may select whether the object is thepower receiver or a simple external object (a key, a coin, etc.). Forsuch a selection, the power transmitter may further perform at least oneof the following phases: the ping phase, theidentification/configuration phase, and the negotiation phase.

In the ping phase, the power transmitter may perform digital ping andwait for the response of the power receiver. The digital ping representsthe application/transmission of the electric power signal to detect andidentify the power receiver. When the power transmitter finds the powerreceiver, the power transmitter may extend the digital ping to proceedto the identification/configuration phase.

In the identification/configuration phase, the power transmitter mayidentify the selected power receiver and obtain configurationinformation of the power receiver, such as a maximum power amount. Inother words, the power transmitter may receive theidentification/configuration information, obtain information on thepower receiver, and use the information to establish a power transfercontract. This power transfer contract may include constraints on aplurality of parameters that characterize power transfer in a subsequentpower transfer phase.

In the negotiation phase, the power receiver may negotiate with thepower transmitter to create an additional power transfer contract. Inother words, the power transmitter may receive a negotiationrequest/information from the power receiver and the negotiation phasemay be performed only if a target receiver is identified as anintermediate power receiver in the identification/configuration phase.In the negotiation phase, additional parameters such as the guaranteedpower level of the power transmitter and the maximum power of the powerreceiver may be negotiated. When the power receiver is a low-powerreceiver, the negotiation phase may be omitted and theidentification/configuration phase may directly proceed to the powertransfer phase.

In the power transfer phase, the power transmitter provides powerwirelessly to the power receiver. The power transmitter receives controldata for transmitted power to control power transfer accordingly. Inaddition, when restrictions of the parameters depending on the powertransfer contract are violated during the power transfer, the powertransmitter may stop the power transfer and proceed to the selectionphase.

FIG. 4 illustrates a power transfer control method in the inductivemode.

In FIG. 4, each of the power transmitter and the power receiver mayinclude a power conversion unit and a power pickup unit, respectively,as illustrated in FIG. 1.

In the power transfer phase of the inductive mode described above, thepower transmitter and the power receiver may control the amount of powertransferred by parallel communication with power transmission andreception. The power transmitter and the power receiver operate at aspecific control point. The control point represents a combination ofvoltage and current provided at an output of the power receiver when thepower transfer is performed.

In more detail, the power receiver selects a desired controlpoint—desired output current/voltage, a temperature of a specificlocation of the mobile device, etc., and determines an actual controlpoint which currently operates at present. The power receiver maycalculate a control error value by using the desired control point andthe actual control point and transmit the control error value as acontrol error packet to the power transmitter.

In addition, the power transmitter sets/controls a new operatingpoint—the amplitude, the frequency, and the duty cycle—by using thereceived control error packet to control the power transfer.Accordingly, the control error packet is transmitted/received at apre-configured time interval in the power transfer phase and as theembodiment, the power receiver may set and transmit a control errorvalue as a negative value in the case of intending to decrease thecurrent of the power transmitter and set and transmit the control errorvalue as a positive value in the case of intending to increase thecurrent. As described above, in the inductive mode, the power receivertransmits the control error packet to the power transmitter to controlthe power transfer.

The resonance mode to be described below may operate in a differentmanner from that in the inductive mode. In the resonant mode, one powertransmitter needs to be able to charge a plurality of power receiverssimultaneously. However, in the case of controlling the power transferas in the inductive mode described above, the power to be transferred iscontrolled by communication with one power receiver, and as a result, itmay be difficult to control the power transfer for additional powerreceivers. Therefore, in the resonant mode of the present invention, amethod is to be used, in which the power transmitter commonly transfersbasic power and the power receiver controls a resonant frequency thereofto control the amount of received power. However, the method describedin FIG. 4 is not completely excluded in the operation of the resonantmode and additional transmission power may be controlled by the methodof FIG. 4.

Shared Mode (Resonant Mode)

FIG. 5 illustrates a power transmission device according to anembodiment of the present invention.

In FIG. 5, the power transmission device may include at least one of acover covering a coil assembly, a power adapter supplying power to thepower transmitter, a power transmitter transmitting wireless power, or auser interface providing power transfer progress and other pertinentinformation. In particular, the user interface may be optionallyincluded or may be included as another user interface of the powertransmission device.

The power transmitter may include at least one of the coil assembly, atank circuit (or impedance matching circuit), an inverter, acommunication unit or a control unit.

The coil assembly includes at least one primary coil that generates themagnetic field and may be referred to as a coil cell.

The impedance matching circuit may provide impedance matching betweenthe inverter and the primary coil(s). The impedance matching circuit maycause resonance at a suitable frequency to boost primary coil current.The impedance matching circuit in a multi-coil power transmitter mayfurther include a multiplexer that routes a signal from the inverter toa subset of the primary coils. The impedance matching circuit may bereferred to as a tank circuit.

The inverter may convert a DC input signal into an AC signal. Theinverter may be driven as a half-bridge or full-bridge to produce apulse wave and the duty cycle of an adjustable frequency. Further, theinverter may include a plurality of stages so as to adjust an inputvoltage level.

The communication unit may perform communication with the powerreceiver. The power receiver performs load modulation to communicate arequest and information for the power transmitter. Thus, the powertransmitter may monitor an amplitude and/or a phase of current and/orvoltage of the primary coil in order to demodulate data transmitted bythe power receiver by using the communication unit. Further, the powertransmitter may control output power to transmit data using a frequencyshift keying (FSK) method or the like through the communication unit. Tothis end, a wireless charger may additionally include a current sensorto detect the receiver by detecting a current change of the primarycoil, and to detect the transmitted data of the detected receiver.

The control unit may control communication and power transfer of thepower transmitter. The control unit may control power transmission byadjusting the operating point. The operating point may be determined,for example, by at least one of an operating frequency, the duty cycle,and an input voltage.

The communication unit and the control unit may be provided as aseparate unit/element/chipset or may be provided as oneunit/element/chipset as illustrated in FIG. 1.

Although not shown in the figure, a Radio Frequency Identification(RFID)/Near Field Communication (NFC) reader unit (or an NFC functionunit) for detecting the RFID/NFC cards may be further mounted on a powertransmitter.

FIG. 6 illustrates a power reception device according to an embodimentof the present invention.

In FIG. 6, the power reception device may include at least one of a userinterface that provides power transfer progress and other pertinentinformation, a power receiver that receives wireless power, a loadcircuit, or a base that supports and covers the coil assembly. Inparticular, the user interface may be optionally included or may beincluded as another user interface of the power transmission device.

The power receiver may include at least one of the power converter, thetank circuit (or impedance matching circuit), the coil assembly, thecommunication unit, and the control unit.

The power converter may convert AC power received from the secondarycoil to voltage and current suitable for the load circuit. As theembodiment, the power converter may include a rectifier. Additionally,the power converter may adapt reflected impedance of the power receiver.

The impedance matching circuit may provide impedance matching between acombination of the power converter and the load circuit and thesecondary coil. As the embodiment, the impedance matching circuit maycause resonance in the vicinity of 100 kHz which may enhance the powertransfer.

The coil assembly may include at least one secondary coil and opticallyfurther include an element that shields a metal portion of the receiverfrom the magnetic field.

The communication unit may perform load modulation for communication ofthe request and other information to the power transmitter. To this end,the power receiver may switch a resistor and a capacitor so as to changereflection impedance.

The control unit may control reception power. To this end, the controlunit may determine/calculate a difference between an actual operatingpoint of the power receiver and a desired operating point. In addition,the control unit may adjust/reduce the difference between the actualoperating point and the desired operating point by requesting adjustmentof the reflection impedance of the power transmitter and/or adjustmentof the operating point of the power transmitter. When the difference isminimized, optimal power reception may be performed.

The communication unit and the control unit may be provided as aseparate element/chipset or may be provided as one element/chipset asillustrated in FIG. 1.

Meanwhile, although not shown in the figure, a Radio FrequencyIdentification (RFID)/Near Field Communication (NFC) reader unit (or anNFC function unit) for detecting the RFID/NFC cards may be furthermounted on a power transmitter.

In the shared mode, the power transmitter needs to manage an exchange ofinformation with one or more power receivers. To this end, the powertransmitter provides a structure for communication with the powerreceiver and such a structure is the same as a communication framedescribed below.

In FIG. 7, the power transmitter provides a structure that provides asequence of time slots in which each power receiver may transmit datapackets. A sync pattern illustrated in FIG. 7 is provided between therespective slots. The sync pattern serves not only to separate theslots, but also to optimize the communication of the power receiver. Inparticular, the sync pattern may provide the receiver with informationfor collision resolution and guaranteed latency.

FIG. 7 illustrates a frame structure for data communication during powertransfer. A shard mode protocol may use two types of frames, i.e., aslotted frame and a free-format frame. The slotted frame may be used forthe power receiver to transmit short data packets to the powertransmitter and the free-format frame may be used for other purposessuch as bi-directional larger data packet transmission and coilselection in the multi-coil transmitter.

All frames start with the sync pattern and a measurement slot and themeasurement slot may be used to measure the transmission power and thereception power. As the embodiment, 9 slots may be included in oneslotted frame. For the free-format frame, there are no specific formatrestriction beyond the sync pattern and the measurement frame. A startbit (information) of a sync packet may indicate the start of the frame.

FIG. 8 is a diagram illustrating a sync packet according to anembodiment of the present invention.

As illustrated in FIG. 8, the sync packet may include at least one of apreamble, a start bit, a response field, a type field, an Info field,and a parity bit.

The preamble includes a sequence of bits set to one. The number of bitsinvolved may vary depending on the operating frequency. The start bitmay be set to zero. The parity bit is a last bit of the sync pattern,and may be set to 1 when the bits set to 1 included in the data fieldsincluded in the sync pattern are even and to 0 otherwise.

The response field may include a response of the transmitter tocommunication from the receiver in a preceding slot. 00 may indicatenon-acknowledge regarding that the communication may not be detected, 01may indicate not-acknowledge regarding that a communication error isdetected, and 10 may indicate not-acknowledge regarding that thecommunication is correctly received, and 11 may indicate acknowledgeregarding that the communication is correctly received.

The type field may be set to 1 for a first sync pattern included in theframe and may be set to 0 for other sync patterns.

The Info field has a different value and meaning according to the syncpattern indicated in the sync field. First, when the type field is 1,the info field may indicate whether the frame is the slotted frame orthe free-format frame. In addition, when the type field is 0, the Infofield may indicate whether a next slot is a slot allocated to a specificreceiver, a slot temporarily provided to a specific receiver, or a freeslot which may be used by any receiver.

FIG. 9 is a diagram illustrating a power transmission method in a sharedmode.

In the shared mode, the power transfer method may include a selectionphase, an introduction phase, a configuration phase, a negotiationphase, and a power transfer phase.

The selection phase may represent a selection phase in the inductivemode illustrated in FIG. 3 and in the shared mode, the selection phasemay be omitted and the remaining four phases may be described. In theshared mode, if the presence of frequency shift keying (FSK) in theelectric power signal is detected before the wake-up timeout, theprocess may proceed directly to the introduction phase.

In the introduction phase, the power receiver may request a free slot totransmit control information (CI) packets to use in the next phases. Tothis end, the receiver transmits an initial CI packet. When the powertransmitter responds with the ACK, the power receiver may proceed to theconfiguration phase. When the power transmitter responds with the NAK,another receiver may perform the configuration phase or the negotiationphase. Therefore, the receiver may request the free slot again. When thereceiver receives the ACK, the receiver may determine a private slotthereof in the frame and thereafter, transmit the CI packet b using theslot at the corresponding location.

In the configuration phase, the power transmitter may provide a seriesof locked slots for exclusive use of the power receiver. This is for thereceiver to perform the configuration phase without a collision. Thereceiver may transmit two identification data packets (IDHI and IDLO),and optionally at least one proprietary data packets, and aconfiguration packet (CFG) using the locked slots. Upon completing sucha phase, the receiver may proceed to the negotiation phase.

In the negotiation phase, the transmitter may also continuously providethe locked slots for exclusive use of the receiver. This is also for thereceiver to perform the negotiation phase without the collision. Thereceiver uses the locked slots to transmit negotiation data packets(including a specific request (SRQ) and a general request (GRQ)) and atleast one optional proprietary data packet. Then, the receiver mayterminate the negotiation phase by transmitting an SRQ/en(SRQ/end-negotiation) packet. When such a phase is terminated, thetransmitter proceeds to the power transfer phase and the transmitterstops providing the locked slots.

In the power transfer phase, the receiver transmits the CI packet usingthe allocated slot. The, the receiver receives the power. The powerreceiver may include a regulator circuit. The regulator circuit may beincluded in the communications and control unit. The receiver mayself-regulate the reflection impedance of the receiver through theregulator circuit. That is, the receiver may adjust the reflectionimpedance so as to transfer the amount of power required for an externalload and prevent reception of excessive power or overheat. In the sharedmode, the transmitter may not adjust the power corresponding to thereceived CI packet according to the operation mode, so that it ispossible to control preventing an over-voltage situation in this case.

Foreign Object Detection (FOD) Extensions

Hereinafter, FOD extension for detecting a foreign object that is not awireless charging object in performing the powertransmission/reception/control method in the inductive mode describedabove with reference to FIGS. 3 and 4 will be described. This FODextension may be performed in such a manner that the negotiation phase,a calibration phase, and a renegotiation phase are added to a basicsystem control method, as illustrated in FIG. 10. The newly added phasesmay mainly perform a function for detecting the foreign object.

FIG. 10 is a diagram illustrating a method for controlling a wirelesspower transmission/reception system to which FOD extension is appliedaccording to an embodiment of the present invention. The description ofeach phase described above with reference to FIGS. 3 and 4 may beapplied in the same or similar manner and hereinafter, differences fromFIGS. 3 and 4 will be mainly described, and duplicated description willbe omitted.

Referring to FIG. 10, in the selection phase, the power transmitter maymonitor an interface surface and monitor the placement and removal ofobjects using small measurement signals. This measurement signal shouldnot wake up the power receiver located on the interface surface. Whenthe power transmitter senses the foreign object on the interfacesurface, the power transmitter needs to remain in the selection phaseand should not provide the electric power signal to prevent overheatingof the foreign object.

In the negotiation phase, the power receiver may negotiate with thepower transmitter to minutely adjust the power transfer contract. Tothis end, the power receiver may transmit a negotiation request to thepower transmitter which the power transmitter may accept or reject. Inaddition, to improve a capability of an initial evaluation of thepresence of the foreign object, the power transmitter may compare aquality factor reported by the power receiver with a measurement value(or signal) thereof. When the power transmitter detects the foreignobject, the process needs to return to the selection phase.

In the calibration phase, the power transmitter may enhance a capabilityto detect the foreign object during power transmission. In particular,the power transmitter may adjust parameters of a power loss method.Here, the power receiver may provide the reception power thereof undertwo load conditions.

In the power transfer phase, the power transmitter may continually checkwhether a new foreign object is placed on the interface surface. To thisend, the power transmitter may use an FOD power loss method based on,for example, a calibrated power loss calculation. The power receiver mayalso check the placement of the new foreign object. When the powertransmitter or power receiver detects the foreign object, the powertransmitter and/or the power receiver must reduce the electric powersignal or remove the electric power signal and return to the selectionphase.

In the renegotiation phase, the power transmitter may adjust the powertransfer contract when desired. If necessary, the renegotiation phasemay be terminated prematurely without changing the power transfercontract.

In the calibration phase, the power transmitter needs to receive fromthe power receiver information which the power transmitter will use toimprove the power loss method for the FOD. In particular, the powertransmitter needs to receive received power information from the powerreceiver and the power receiver at this time transmits the receivedpower information at a light load (disconnected load) and a connectedload. If the power transmitter does not receive such received powerinformation, the power transmitter may remove the electric power signaland return to the selection phase. However, the power transmitter mayattempt to improve the power loss method by using the received powerinformation only when it is confirmed that there is no foreign object.

The operation of the power transmitter in the calibration phase may bethe same as the operation in the power transfer phase, but the followingoperations may be added.

-   -   If the power transmitter receives a 24-bit received power packet        with the mode field set to ‘001’ (calibration mode for the light        load) and if the received power value is met, the power        transmitter may transmit an ACK response. Otherwise, the power        transmitter may transmit an NAK response.    -   If the power transmitter receives a 24-bit received power packet        with the mode field set to ‘010’ (calibration mode for the        connected load) and if the received power value is met, the        power transmitter may transmit the ACK response and continuously        perform the power transfer phase. Otherwise, the power        transmitter may transmit the NAK response.

Here, the received power packet (RPP) may correspond to a packettransmitted to the power transmitter at least once by the power receiverin the negotiation phase in order to change the format of the receivedpower packet determined in the power transfer contract. When the powertransmitter transmits the ACK response to the received power packet, theformat of the received power packet in a provisional power transfercontract may be changed based on the received power packet in which theACK response is transmitted.

NFC/RFID Detection Method

When a Radio Frequency Identification (RFID) card or a Near FieldCommunication (NFC) card is placed between a power transmitter (e.g.,wireless charger) and a power receiver (e.g., mobile device, etc.), apower transmitter without having RFID/NFC detection function cannotdetect an RFID/NFC card. In addition, even with the FOD method definedby WPC, which is a standard for a wireless power transmission/receptionsystem, the power transceiver cannot detect the RFID/NFC card. Thereason is that the FOD method defined in the WPC is defined to detectforeign object based on how much power transmitted from the powertransmitter to the power receiver is lost (e.g., if the transmissionefficiency is below a pre-configured level), but in the case of anRFID/NFC card, even if it is placed between the power transmitter andthe power receiver, power loss does not occur. Furthermore, since theoperating frequency (e.g., about 100 to 205 kHz) of the electric powertransceiver defined in the WPC is different from the operating frequencyof the RFID/NFC card (e.g., about 13.56 MHz), even with the frequency itis difficult to detect the RFID/NFC card.

If the wireless power transceiver fails to detect the presence of theRFID/NFC card and maintains the power transmission, there exists theproblem that the RFID/NFC card continuously exposed to a strong magneticfield may eventually be damaged and causes financial/property damage toa user. Furthermore, stability problems due to the heat generation ofthe RFID/NFC card can be raised.

Therefore, in the present specification, a method for detecting such anRFID/NFC card will be proposed. The description of the embodimentsproposed herein can be cooperated with the WPC Qi wireless powertransmission system power class 0 specification Version 1.2.3 andVersion 1.3.

As one embodiment, since most of the power receivers (for example,mobile devices, smart phones, etc.) that are recently released haveembedded NFC functions, the power receiver uses the function to detectRFID/NFC cards. Using this function, a power receiver that detects anRFID/NFC card can transfer the RFID/NFC detection information to thepower transmitter, and the power transmitter can stop power transmissionand guide the user to remove the RFID/NFC card.

In order to detect the RFID/NFC card using the NFC function built in thepower receiver, the protocol promised in advance for the powertransmission/reception period needs to be defined. In order to applythis to a wireless power system standardized by WPC, compatibility witha protocol/packet already defined in the WPC standard should bemaintained. However, in the WPC standard up to now, the packet fortransferring the RFID/NFC detection information from the power receiverto the power transmitter has not separately defined.

Accordingly, hereinafter, using an NFC function of a power receiver, anew protocol between a power transmitter and receiver for detecting anRFID/NFC card is defined, and the embodiment is proposed in which invarious packets (e.g., a capability packet, an end power transfer (EPT)packet, a configuration packet, etc.) pre-defined in the WPCspecification for the compatibility with the WPC specification, a newfield/bit (e.g., RFID/NFC detection field/bit, etc.) is defined, and itis used for the protocol.

In the wireless power transmission and reception system, the NFC/RFIDdetection of the power receiver can proceed as follows.

1. If the power receiver is placed on a power transmitter (i.e., thepower receiver is located in the charging area of the powertransmitter), the power transmitter can detect the power receiver andwake up the power receiver using the digital ping.

2. The power receiver waken up enters the power transfer phase throughvarious phases according to the power transfer method/protocol definedin the WPC specification (refer to FIGS. 3 and 10).

3. The power receiver entering the power transfer phase performs theRFID/NFC detection operation, and it is necessary to obtain time forperforming the detection operation. Also, during the RFID/NFC detectionof the power receiver, it is necessary to stop the power transferoperation of the power transmitter. The reason is that the magneticfield formed by the power transmitted from the power transmitter is aninterference/disturbance for the power receiver to perform the NFC/RFIDdetection operation.

For this reason, the power receiver may transmit an EPT packetinstructing the power transmitter to stop the power transmission for acertain amount of time (in this case, the value of the EPT packet can beset as 0x0C (=indicating re-ping)) (in the negotiation phase), and thusthe power transmitter can restart from the digital ping transmissionagain after a certain amount of time. The certain amount of time for thepower transmitter to stop the power transfer may be set using a re-pingtime packet (which may be transmitted in the negotiation/renegotiationphase) (also referred to as a ‘re-ping’ packet), which will be describedbelow.

4. The power receiver can perform RFID/NFC detection by activating theembedded NFC function. If the power transmitter enters the powertransfer phase (or charging mode) by retransmitting the digital pingduring RFID/NFC detection of the power receiver, the power receiver cantransmit an EPT packet (in this case, the value of the EPT packet may beset as 0x0C (=re-ping)) to the power transmitter again (in this case,the value of the EPT packet may be set to 0x0C (=re-ping)) to extend thedetection time.

5. If the NFC/RFID card is detected, when the power receiver enters thepower transfer mode (or the charging mode) (after the expiration of thecertain amount of time), the power receiver can generate/transmit an EPTpacket (NFC detection) including information indicating that theRFID/NFC card has been detected, thereby causing the power transmitterto stop transferring power. Upon receiving this EPT packet, the powertransmitter can stop power transfer and induce/guide a user to removethe NFC/RFID card using a user interface.

6. If the NFC/RFID card is not detected, the power receiver deactivatesthe embedded NFC function (to prevent damage to the embedded NFCfunctionality due to the strong magnetic field created by the powertransmitter during charging), and then the power transfer phase (orcharging mode) can be continued.

That is, upon checking the above-mentioned RFID/NFC detection method,when the power receiver detects the NFC/RFID card using the embedded NFCfunction, the electric power signal provided from the power transmittercan act as an interference signal, it is necessary to temporarily stoptransmission of the electric power signal. Thus, in order to obtain thenecessary for RFID/NFC detection, the power receiver can transmit an EPTpacket (indicating a re-ping) pre-defined in the WPC specification toensure that the power transmitter has to stop transferring power for acertain amount of time. The power receiver may perform RFID/NFCdetection for a period of time during which the power transfer isinterrupted, and then transmit the detection result to the powertransmitter through an EPT packet (including NFC/RFID detectioninformation). Upon receiving the EPT packet (RFID/NFC detection)including the result that the RFID/NFC card is detected, the powertransmitter can stop transmitting power, thereby guiding a user toremove the RFID/NFC card (using a user interface or the like).

In this manner, the power receiver can detect/protect the RFID/NFC cardusing the embedded NFC function. To support this operation, a new EPTvalue/code is defined so that NFC detection information can be displayedin the existing EPT packet.

FIG. 11 illustrates an EPT packet format defined in the current WPCstandard.

The EPT packet may contain an EPT value/code defined as shown in Table 1below.

TABLE 1 Recommended usage of the values Reason Value (Informative)Unknown 0x00 The Receiver may use this value if it does not have aspecific reason for terminating the power transfer or if none of theother values listed in this table is appropriate Charge 0x01 TheReceiver should use this value if it Complete) determines that thebattery of the Mobile Device is fully charged On receipt of an End PowerTransfer Packet containing this value, the Transmitter should set any“charged” indication on its user interface that is associated with theReceiver Internal 0x02 The Receiver may use this value if it has Faultencountered some internal problem (e.g. a software or logic error) Over0x03 The receiver should use this value if it has Temperature measured atemperature within the mobile device that exceeds a limit Over Voltage0x04 The Receiver should use this value if it has measured a voltagewithin the mobile device that exceeds a limit Battery 0x06 The Receivershould use this value if it has Failure determined a problem exists withthe Mobile Device battery Reserved 0x07 The End Power Transfer Value =0x07 (reconfigure) has been deprecated and should not be used. It mayresult in unpredictable Power Transmitter behavior No Response 0x08 TheReceiver should use this value if it determines that the Transmitterdoes not respond to Control Error Packets as expected (e.g. it does notincrease or decrease its Primary Cell current appropriately) Reserved0x09 — Negotiation 0x0A A power receiver should use this value if itcannot Failure negotiate a suitable Guaranteed power level (ExtendedPower Profile only) Restart Power 0x0B A power receiver should use thisvalue if sees a Transfer need for Foreign Object Detection with no powertransfer in (Extended progress (see Section 11.3, FOD based on qualityPower Profile factor change). To enable such detection, the only) powertransfer has to be terminated. Typically, the power transmitter thenperforms Foreign Object Detection before restarting the power transfer.Reserved 0x0C — to 0xFF

In other words, the EPT packet itself indicates complete/stop request inthe power transfer, and in the EPT packet, as shown in Table 1, an EPTcode/value indicating the reason why the power receiver requests thepower transmitter to complete/stop power transfer can be transmitted tobe carried.

Of these EPT values/codes, a specific code can be used/set as avalue/code indicating the RFID/NFC detection result. For example,‘0x0D’, which is currently set as the reserved bit, can be set/used as avalue/code indicating that the RFID/NFC is detected. In this case, adescription of 0x0D may be added as shown in Table 1 below.

-   -   Reason: NFC/RFID detected, value: 0x0D, Recommended usage of the        values (Informative): Power Receiver detected RFID/NFC card/tag        in the proximity.

In this example, the power transmitter receiving the EPT packetindicated 0x0D stops power transfer/transmission and can notify the userthat the RFID/NFC card/tag is present in the charging area to induceRFID/NFC card/tag removal in the charging area.

Also, 0x0C of the reserved bits may be used/set as an EPT value/coderequesting to stop power transmission for a certain amount of time (forexample, a re-ping time).

This EPT packet may be transmitted from the power receiver to the powertransmitter at a specific phase of the WPC protocol (e.g., a ping phaseor a negotiation phase).

In the above-described embodiment, the power receiver has been mainlydescribed as an entity performing the RFID/NFC detection operation, butthe present invention is not limited thereto, and the power transmittermay also function as an entity performing the RFID/NFC detectionoperation. However, in order to perform the RFID/NFC detectionoperation, the power transmitter also assumes an RFID/NFC reader unit(or an NFC functional unit) capable of detecting RFID/NFC (in proximity)to be embedded/mounted.

Hereinafter, an embodiment in which the power receiver and the powertransmitter selectively function as an entity performing the RFID/NFCdetection operation will be described.

In another embodiment, either the power transmitter or the powerreceiver can selectively perform the RFID/NFC detection operationdepending on whether the power transmitter has RFID/NFC detectioncapability.

In order for the power receiver to determine whether to activate the NFCfunction embedded therein, the power receiver needs to know whether thepower transmitter is capable of detecting the RFID/NFC. Accordingly, thepower transmitter can inform whether or not it has RFID/NFC detectioncapability in the negotiation phase and whether the RFID/NFC has beendetected if it has the detection capability to the power receiverthrough the capability packet.

If the power transmitter informs the power receiver (at the negotiationphase) that ‘it has the capability of detecting RFID/NFC and hasdetected the RFID/NFC’, the power receiver will guide a user to removethe RFID/NFC card (in proximity).

When the power transmitter informs the power receiver (at thenegotiation phase) that there is no RFID/NFC detection capability, thepower receiver can perform the RFID/NFC detection operation. In thiscase, the power receiver may transmit an EPT packet (0x0C (=re-ping) toremove/turn off the transmit electric power signal of the powertransmitter, which may interfere/disturb with the RFID/NFC detection fora certain amount of time (e.g. re-ping time) to the power transmitter.The power receiver can be configured to: (1) fit into the WPC protocol(power transfer protocol/scheme defined in the WPC specification); and(2) detect the RFID/NFC card/tag, while the power transmitter stopspower transmission to prevent interference/disturbance of the NFCfunction. The certain amount of time at which the power transmission isstopped may be defined as a re-ping time, and this re-ping time may benegotiated/indicated by the re-ping time packet. The example for there-ping time packet format will be described below with reference toFIG. 23.

During transmission of the electric power signal is stopped, the powerreceiver can detect the RFID/NFC card/tag in the proximity positionusing the embedded NFC function. A detailed description for thedetection method is as described above.

When the power transmitter resumes the WPC protocol from the ping stageafter a certain amount of time (e.g., re-ping time) has expired, if thepower receiver has detected the RFID/NFC card in proximity for thecertain amount of time (e.g., re-ping time), it may transmit an EPTpacket (e.g., set to 0x0D) (e.g., a configuration packet, a specificrequest packet) indicating that an RFID/NFC has been detected to stopthe WPC protocol to the power transmitter. Further, the powertransmitter and/or power receiver may inform the user to remove theRFID/NFC card/tag in the proximity location. Otherwise, the powerreceiver can proceed to the WPC protocol and receive power from thepower transmitter.

In order for the above-described embodiment to be compatible with thewireless power transmission/reception system defined in the WPCstandard, it is necessary to define new fields/bits indicating whetherthe power transmitter has RFID/NFC detection capability and/or whetherthe RFID/NFC has been detected in a capability packet carryingcapability information of the power transmitter. Various embodimentsrelating to the new format of this capability packet will be describedlater in detail in FIGS. 12 to 16. The bit/field names of each packetillustrated in the present specification may vary according to theembodiment, and it is obvious that if the functions are the same, theycan be regarded as the same bit/field even if the names are different.

FIG. 12 illustrates a capability packet format according to a firstembodiment of the present invention.

Referring to FIG. 12, the capability packet (0x31) includes variouscapability information related to the power transfer of the powertransmitter. For example, the capability packet includes a power classbit/field (2 bits), a guaranteed power value bit/field (6 bits), apotential power value bit/field (6 bits), a Wireless Power Identifier(WIPID) bit/field (1 bit), Not Res Sens. bit/field (1 bit) and/or an NFCdetection/protection bit/field (2 bits). Here, the NFCdetection/protection bits/field may be configured using at least some ofthe reserved bits in the capability packet that are pre-defined in theWPC specification.

The power class bits/field indicates the power class of the wirelesspower transmission and reception system. This bit/field can be set to avalue of ‘00’ (indicating class 0).

The guaranteed power value bit/field indicates the maximum guaranteedpower value included in the power transfer contract (PTC-GP) that thepower transmitter can negotiate in the current ambient conditions. Here,the ambient conditions may include, for example, the temperature of thepower transmitter, the amount of power obtained from a power source thatthe power transmitter shares with other power transmitters, and/orwhether or not there is a foreign substance or friendly metal materialor the like. The guaranteed power value bit/field indicates the powervalue in units of 0.5 W

The potential power value bit/field indicates the maximum guaranteedpower value included in the power transmission contract (PTC-GP) thatthe power transmitter can negotiate under ideal ambient conditions. Thisfield also indicates the power value in units of 0.5 W.

The Not Res Sens. bit/field may be set to a different value for eachdesign of an individual power transmitter. In general, this bit/fieldmay be set to a value of ‘0’ to indicate a power transmitter designcapable of frequency control below 150 kHz with a power transfercontract that includes a maximum power value greater than 5 W.

The WPID bit/field indicates that the power transmitter is capable ofreceiving WPID packets.

The NFC detection/protection bit/field may indicate whether the powerreceiver has a capability of detecting RFID/NFC and/or whether anRFID/NFC card/tag has been detected. The NFC detection/protectionbit/field may be composed of 2 bits size, and the bit indicated by eachbit/field value can be illustrated as follows.

-   -   00b: The power transmitter has no capability of detecting        RFID/NFC (card/tag).    -   01b: reserved bit/field    -   10b: The power transmitter has a capability of detecting        RFID/NFC (card/tag), and RFID/NFC is not detected (in proximity        location).    -   11b: The power transmitter has a capability of detecting        RFID/NFC and RFID/NFC is detected (in proximity location).

The information indicated by each bit/field value is only an example,and the bit/field value indicating each information may be changedaccording to the embodiment.

The next operation of the power receiver receiving the NFCdetection/protection bit/field value according to the above example isthe same as the example of FIG. 13.

FIG. 13 is a table illustrating a next operation of a power receiverreceiving an NFC detection/protection bit/field according to anembodiment of the present invention.

Referring to FIG. 13, when the power receiver receives an NFCdetection/protection bit/field (indicating that the power transmitterhas no capability of detecting RFID/NFC (card/tag)) set to a value of‘00’, it may transmit an EPT packet to perform the RFID/NFC detection tothe power transmitter (this is to secure the RFID/NFC detectionexecution time and to remove the electric power signal which mayinterfere with the RFID/NFC detection, as described above). Morespecifically, in order to detect the RFID/NFC card/tag, the powerreceiver may transmit a re-ping time packet and/or an EPT (set to OxOc(=re-ping)) packet to the power transmitter. Here, the re-ping timepacket indicates a packet for setting a re-ping time (duration/period)at which the power transmitter stops transmitting the electric powersignal, this re-ping time packet will be described in detail below withreference to FIG. 23 will be described later. The RFID/NFC detectionoperation of the power receiver below follows the NFC/RFID detectionmethod of the power receiver described above.

When the power receiver receives an NFC detection/protection bit/field(reserved bit/field) set to a value of ‘01’, it corresponds to a sparebit and the power receiver does not take any action or may transmit theEPT packet to remove an electric power signal.

If the power receiver has received an NFC detection/protection bit/fieldset to a value of ‘10’ (indicating that the power transmitter has acapability of detecting RFID/NFC and the RFID/NFC has not been detected(in proximity location)), a calibration step may be proceeded to receivepower from the power transmitter.

If the power receiver has received an NFC detection/protection bit/fieldset to a value of ‘11’ (indicating that the power transmitter has acapability of RFID/NFC and that the RFID/NFC has been detected (inproximity location)), it may be notified a user to remove the NFCcard/tag. Further, the power receiver and/or power transmitter mayrefrain from entering the power transfer phase until the detectedRFID/NFC card/tag is removed.

FIG. 14 illustrates a capability packet format according to a secondembodiment of the present invention.

Referring to FIG. 14, the capability packet 0x31 includes a power classbit/field (2 bits), a guaranteed power value bit/field (6 bits), apotential power value bit/field (6 bits), a WPID bit/field (1 bit), aNot Res Sens. bit/field (1 bit), an NFC Protection Present (NFCPP)bit/field (1 bit) and/or an NFC Detected (NFCD) bit/field (1 bit). Here,as a description for the power class bit/field, the guaranteed powervalue bit/field, the potential power value bit/field, the WPIDbit/field, and the Not Res Sens bit/field (1 bit) has been describedabove with reference to FIG. 12, and thus redundant description will beomitted. The NFCPP bit/field and the NFCD bit/field may be configuredusing at least some of the reserved bits in the capability packet thatare pre-defined in the WPC specification.

The NFCPP bit/field may indicate whether the power transmitter has acapability of detecting RFID/NFC. The NFCPP bit/field may be composed of1 bit size, and the bit indicated by each bit/field value can beillustrated as follows.

-   -   0: The power transmitter has no capability of detecting RFID/NFC        (card/tag).    -   1: The power transmitter has a capability of detecting RFID/NFC        (card/tag).

The NFCD bit/field may indicate whether the power transmitter hasdetected an RFID/NFC (card/tag). The NFCD bit/field may be composed of1-bit size, and the bit indicated by each bit/field value can beillustrated as follows.

-   -   0: The power transmitter has not detected RFID/NFC (card/tag)        (in proximity location).    -   1: The power transmitter has detected RFID/NFC (card/tag) (in        proximity location).

The information indicated by each bit/field value is only an example,and the bit/field value indicating each information may be changedaccording to the embodiment.

The next operation of the power receiver receiving the NFCPP and NFCDbit/field values according to the above example is the same as theexample of FIG. 15.

FIG. 15 is a table illustrating the next operation of a power receiverthat has received NFCPP and NFCD bits/fields according to an embodimentof the present invention.

Referring to FIG. 15, when the NFCPP and the NFCD bits/field (total 2bits) are received with the capability packet set to a value of ‘00’ (or‘01’), the power receiver transmits an EPT packet to perform theRFID/NFC detection to the power transmitter (this is for the purpose ofsecuring the RFID/NFC detection execution time and eliminating theelectric power signal which may interfere/disturb with the RFID/NFCdetection, as described above). More specifically, in order to detectthe RFID/NFC card/tag, the power receiver may transmit a re-ping timepacket and/or an EPT (set to OxOc (=re-ping)) packet to the electricpower. The RFID/NFC detection operation of the power receiver belowfollows the NFC/RFID detection method of the power receiver describedabove.

When the NFCPP and the NFCD bit/field are set to a value of ‘10’; andthe capability packet is received, the power receiver may proceed with acalibration step to receive power from the power transmitter.

If the power receiver has received the capability packet with the NFCPPand the NFCD bit/field set to a value of ‘11’, the power receiver mayguide the user to remove the RFID/NFC card/tag. Further, the powerreceiver and/or power transmitter may refrain from entering the powertransfer phase until the detected RFID/NFC card/tag is removed.

As described above, in order to determine whether the power transmitterhas detected the RFID/NFC, the power receiver may transmit a generalrequest packet requesting the capability packet including the NFCPPand/or NFCD bit/field, or it may transmit a specific request packethaving a newly defined request code, and thus it may confirm whether thepower transmitter has detected/capability of detecting the RFID/NFC. Forexample, the power receiver may transmit a specific request packetincluding a request field with a code/value of 0x05 to the powertransmitter, and thus it may inquire to the power transmitter whetherthe RFID/NFC has been detected.

The power transmitter receiving the specific request packet may transmit

-   -   ACK (or NACK (Negative Acknowledge)) response if it has not        detected an RFID/NFC (card/tag)    -   NACK (or ACK) response if it has detected the RFID/NFC        (card/tag)    -   ND (Not Defined) response if it has not known whether the        RFID/NFC (card/tag) exists or not (for example, if the power        transmitter does not understand a new request included in the        specific request packet), respectively.

If the ND response has been received, in order to perform RFID/NFCdetection, the power receiver may transmit an EPT packet to the powertransmitter (this is for the purpose of securing the RFID/NFC detectionexecution time and eliminating the electric power signal which mayinterfere/disturb with the RFID/NFC detection, as described above). Morespecifically, in order to detect the RFID/NFC card/tag, the powerreceiver may transmit a re-ping time packet and/or an EPT (set to OxOc(=re-ping)) packet to the electric power. The RFID/NFC detectionoperation of the power receiver below follows the NFC/RFID detectionmethod of the power receiver described above.

If the ACK response has been received, the power receiver may proceedwith a calibration step to receive power from the power transmitter.

If the NACK response has been received, the power receiver may guide auser to remove the RFID/NFC card/tag. Further, the power receiver and/orpower transmitter may refrain from entering the power transfer phaseuntil the detected

RFID/NFC card/tag is removed.

FIG. 16 illustrates a capability packet format according to a thirdembodiment of the present invention.

Referring to FIG. 16, the capability packet 0x31 includes a power classbit/field (2 bits), a guaranteed power value bit/field (6 bits), apotential power value bit/field (6 bits), a WPID bit/field (1 bit) a NotRes Sens. bit/field (1 bit), and/or an NFC protection bit/field (1 bit).Here, as a description for the power class bit/field, the guaranteedpower value bit/field, the potential power value bit/field, the WPIDbit/field, and a Not Res Sens. bit/field (1 bit) has been describedabove with reference to 12, and thus redundant description will beomitted. The NFC protection bits/field may be configured using at leastsome of the reserved bits in the capability packet set in the WPCspecification.

The NFC protection bit/field may indicate whether the power transmitterhas a capability of detecting RFID/NFC detection and whether it hasdetected the RFID/NFC. The NFC protection bit/field may be composed of1-bit size, and the contents indicated by each bit/field value can beillustrated as follows.

-   -   0: The power transmitter has no capability of detecting RFID/NFC        (card/tag)    -   1: The power transmitter has a capability of detecting the        RFID/NFC (card/tag) but has not detected the RFID/NFC (card/tag)        (in proximate location).

When the power receiver receives an NFC protection bit/field set to avalue of ‘0’, in order to perform RFID/NFC detection, it can transmit anEPT packet to the power transmitter (this is for the purpose of securingthe RFID/NFC detection execution time and eliminating the electric powersignal which may interfere/disturb with the RFID/NFC detection, asdescribed above). More specifically, in order to detect the RFID/NFCcard/tag, the power receiver may transmit a re-ping time packet and/oran EPT (set to 0x0c (=re-ping)) packet to the power transmitter. TheRFID/NFC detection operation of the power receiver below follows theNFC/RFID detection method of the power receiver described above

If the power receiver has received an NFC protection bit/field set to avalue of ‘1’, it may proceed with a calibration step to receive powerfrom the power transmitter.

Hereinafter, a more specific embodiment in which the power transmitterand/or power receiver detects the RFID/NFC (card/tag) will be describedwith reference to the respective drawings.

FIG. 17 illustrates an RFID/NFC detection method of a power receiveraccording to the first embodiment of the present invention. Inparticular, FIG. 17 (a) illustrates the operation/phase of the powerreceiver without the RFID/NFC detection function and FIG. 17 (b)illustrates the RFID/NFC detection operation/step of the power receiverwith RFID/NFC detection function. In the figure, the horizontal axisrepresents the time and the vertical axis represents the amount ofpower.

Referring to FIG. 17 (a), a power receiver without RFID/NFC detectionfunction can receive power according to a general WPC protocol. Thedescription of a ping phase (analog ping and digital ping transmission),an identification/configuration phase, a negotiation phase, acalibration phase and a power transfer phase defined in the WPC protocolis as described above in FIGS. 3, 9 and 10. In this embodiment, insteadof the power receiver without the RFID/NFC detection function, the powertransmitter with the RFID/NFC detection function can perform theRFID/NFC detection operation.

Referring to FIG. 17 (b), a power receiver with RFID/NFC detectioncapability may transmit an EPT packet (set to as 0x0C or indicating there-ping) to stop the power transfer of the power transmitter during there-ping time, in the negotiation phase (or after the negotiation phase).The power transmitter receiving the EPT packet (set to as 0x0C orindicating the re-ping) may stop transmitting power with the powerreceiver during the negotiated re-ping time in the negotiation phase. Inaddition, the power receiver can activate the embedded NFC functionduring the re-ping time and thus performing the RFID/NFC detectionoperation (in proximate location).

When the re-ping time expires, the power transmitter may transmit adigital ping to wake up the power receiver to resume the WPC protocolfor power transfer.

If the RFID/NFC (card/tag) has not been detected during the re-pingtime, the power receiver may proceed with the general WPC protocolsequentially to receive power from the power transmission.

If an RFID/NFC (card/tag) has been detected during the re-ping time, thepower receiver can inform the power transmitter of the detection result.More specifically, in order to prevent damage to the detected RFID/NFC(card/tag), the power receiver can inform the RFID/NFC (card/tag)detection result such that the power transmitter stops power transfer.The power receiver can transmit the RFID/NFC detection result to thepower transmitter through a ‘configuration packet’ transmitted/receivedin the identification/configuration phase or a ‘specific request packet’transmitted/received in the negotiation step. Examples of suchconfiguration packets and specific request packet formats are describedbelow in detail below with respect to FIGS. 24 and 25.

Upon receiving the detection result that the RFID/NFC (card/tag) hasbeen detected from the power receiver, the power transmitter can removethe electric power signal that is being transmitted.

FIG. 18 is a flowchart showing the embodiment of FIG. 17 in terms ofoperation of a power transmitter and a power receiver.

Referring to FIG. 18, the power receiver may transmit a General Request(GR) packet (0x31) to the power transmitter in the negotiation phase (orafter the negotiation phase) (S18010). The general request packet mayinclude information requested by the power receiver. In the case of thepresent embodiment, in order to determine whether the power transmitteris equipped with the RFID/NFC detection capability, the power receivermay request capability information/packets for the RFID/NFC detectioncapability of the power transmitter through a general request packet.

Next, as a response to the general request packet, the power transmittermay transmit a capability packet including its RFID/NFC detectioncapability information to the power receiver (S18020). The format of thecapability packet may follow the embodiment described above in FIGS. 12,14 and 16, and the operation of the power receiver according to thereceived capability packet information may follow the embodimentdescribed above in FIGS. 13, 15 and 16. In this flowchart, it isdescribed in the assumption that the capability packet format followsthe embodiment of FIG. 16 and that the power transmitter does not havecapability of detecting the RFID/NFC. Thus, in order to indicate that itis not equipped with RFID/NFC detection capability, the powertransmitter may set the NFC protection bit/field in the capabilitypacket to a value of ‘0’ (or ‘O’ b) and transmit it to the powerreceiver.

Next, in order to secure time to perform the RFID/NFC detectionoperation, the power receiver may transmit a re-ping time packet and/oran EPT packet to the power transmitter, to instruct the powertransmitter to stop the power transmission (S18030). In principle, there-ping time packet is used to set the re-ping time, and the EPT packetis used to stop the power transmission of the power transmitter,respectively. However, in order to reduce the time/signaling overhead, anew re-ping time packet format may be defined that sets a re-ping timeand requests a power transmission interruption during a re-ping time,and it will be described for this format in detail below. In thisflowchart, the ‘Immed’ bit/field value in the re-ping time packet is setto ‘1’, and It is assumed that this re-ping time packet indicates there-ping time, and at the same time, the packet is functioned as a packetrequesting the power transmission interruption.

Next, the power receiver can perform the RFID/NFC detection operationusing the embedded NFC function during the re-ping time (S18040). Oncethe set re-ping time expires, the power transmitter and power receivermay perform the ping phase and the identification/configuration phase.

Next, the power receiver can report the RFID/NFC detection result to thepower transmitter via the configuration packet or the specific requestpacket. The embodiment for a configuration packet or a specific requestpacket format will be described below with reference to FIGS. 24 and 25below.

If the power receiver has detected an RFID/NFC (card/tag), the powertransmitter can transmit the configuration packet or specific requestpacket including the detection result during or after theidentification/configuration phase) such that the electric power canremove the electric power signal (or stop the power transmission)(S18050). As will be described later, the NFC protection bit/field valuein the configuration packet transmitted in this case may be set to ‘1’b,and the request bit/field value in the specific request packet may beset to ‘0x05’. Upon receiving the configuration packet or the specificrequest packet, the power transmitter can immediately remove theelectric power signal (or stop the power transfer) and guide a user toremove the detected RFID/NFC (card/tag).

FIG. 19 illustrates an RFID/NFC detection method of a power receiveraccording to a second embodiment of the present invention. Inparticular, FIG. 19 (a) illustrates the operation/phase of the powerreceiver without the RFID/NFC detection function and FIG. 19 (b)illustrates the operation/phase of the power receiver with the RFID/NFCdetection function. The description of this embodiment can be applied inthe same/similar manner for the description of the first embodimentdescribed above with reference to FIG. 17, and the following descriptionwill focus on differences from the first embodiment. In the figure, thehorizontal axis represents the time and the vertical axis represents theamount of power.

In the case of the second embodiment, unlike the first embodiment, thereis a difference in that the electric power signal interruption time isbefore the calibration step (or during the negotiation step) (for in thefirst embodiment, it is during or after the identification/configurationphase). The difference for this point in time is resulted from that (1)the point in time at which the power level started to be transmitted tothe power receiver starts from the calibration step, and (2) theinformation that the RFID/NFC (card/tag) has been detected istransmitted to the power transmitter through the EPT packet (set to0x0D), which will be described later in detail with reference to theflowchart of FIG. 20.

FIG. 20 is a flowchart showing the embodiment of FIG. 19 in terms ofoperation of a power transmitter and a power receiver. The descriptionof this flowchart may be applied in the same/similar manner for thedescription of the first embodiment described above with reference toFIG. 18, and the following description will focus on differences fromthe first embodiment.

Referring to FIG. 20, in order to confirm the RFID/NFC detectioncapability of the power transmitter in the negotiation step, the powerreceiver may transmit a general request (GR) packet (0x31) (S20010).

Next, as a response to the general request packet, the power transmittermay transmit the capability packet including its RFID/NFC detectioncapability information to the power receiver (S20020). In thisflowchart, it is described in the assumption that the capability packetformat follows the embodiment of FIG. 16 and that the power transmitterdoes not have capability of detecting the RFID/NFC. Thus, in order toindicate that it is not equipped with RFID/NFC detection capability, thepower transmitter may set the NFC protection bit/field in the capabilitypacket to a value of ‘0’ (or ‘O’ b) and transmit it to the powerreceiver

Next, in order to secure time to perform the RFID/NFC detectionoperation, the power transmitter transmits a re-ping time packet and/oran EPT packet (set to as 0x0C or indicating the re-ping) to instruct thepower transmitter to stop the power transmission (S20030). The Re-pingtime packet format may follow the embodiment of FIG. 23, and the EPTpacket format may follow the embodiment of FIG. 11. This phase may beperformed before the calibration phase (e.g., in the negotiation phase)and this is for the power receiver to secure enough time to detect theRFID/NFC (card/tag) in advance, before the calibration phase where amagnetic field is strong enough to damage the RFID/NFC (card/tag).

Next, the power receiver may perform the RFID/NFC detection operationusing the embedded NFC function during the re-ping time (S20040). Oncethe set re-ping time expires, the power transmitter and power receivermay perform the ping phase, the identification/configuration phase, andthe negotiation phase.

Next, when the power receiver has detected the RFID/NFC (card/tag), theEPT packet (set to as 0x0D) (or configuration packet) including thedetection result is transmitted to the power transmitter (duringnegotiation phase or identification/configuration phase), and thusallowing the power transmitter to remove the electric power signal (orstop power transfer) (S20050). Upon receiving the EPT packet (set to as0x0D), the power transmitter may refrain from entering the calibrationphase and remove the electric power signal (or stop power transfer).Furthermore, the power transmitter can guide a user to remove thedetected RFID/NFC (card/tag).

FIG. 21 illustrates an RFID/NFC detection method of a power receiveraccording to a third embodiment of the present invention. In particular,FIG. 21(a) illustrates the operation/phase of a power receiver withoutthe RFID/NFC detection function, and FIG. 21(b) illustrates theoperation/phase of a power receiver with the RFID/NFC detectionfunction. The description of this embodiment can be applied in thesame/similar manner, compared with description of the first embodimentdescribed above with reference to FIG. 17, and the following descriptionwill focus on differences from the first embodiment. In the figure, thehorizontal axis represents the time and the vertical axis represents theamount of power.

In the case of the third embodiment, unlike the first embodiment, thereis a difference in that the time of stopping electric power signal isduring the ping phase (for in the first embodiment, it is during orafter the identification/configuration phase).

FIG. 22 is a flowchart showing the embodiment of FIG. 21 in terms ofoperation of a power transmitter and a power receiver. The descriptionof this flowchart can be applied in the same/similar manner, comparedwith the first embodiment described above with reference to FIG. 18, andthe following description will focus on differences from the firstembodiment.

Referring to FIG. 22, in order to confirm the RFID/NFC detectioncapability of the power transmitter in the negotiation step, the powerreceiver may transmit a general request (GR) packet (0x31) (S22010).

Next, to confirm the RFID/NFC detection capability of the powertransmitter in the negotiation step, the power transmitter may transmita capability packet including its own RFID/NFC detection capabilityinformation to the power receiver (S22020). In this flowchart, it isdescribed in the assumption that the capability packet format followsthe embodiment of FIG. 16 and that the power transmitter does not havethe RFID/NFC detection capability. Thus, in order to indicate that theRFID/NFC detection capability is not equipped with, the powertransmitter may set the NFC protection bit/field in the capabilitypacket to a value of ‘0’ (or ‘0’b) and transmit it to the powerreceiver.

Next, in order to secure time to perform the RFID/NFC detectionoperation, the power transmitter transmits a re-ping time packet and/oran EPT packet (which is set to as 0x0C or indicating the re-ping) toinstruct the power transmitter to stop the power transmission. (S22030).The re-ping time packet format may follow the embodiment of FIG. 23, andthe EPT packet format may follow the embodiment of FIG. 11. This stepmay be performed before the calibration phase (e.g., the negotiationphase), which may be performed before the RFID/NFC (card/tag)calibration phase, before the calibration step where the magnetic fieldis strong enough to damage the RFID/Tag) in order to ensure that thepower receiver has enough time to detect it. This phase may be performedbefore the calibration phase (e.g., in the negotiation phase) and thisis for the power receiver to secure enough time to detect the RFID/NFC(card/tag) in advance, before the calibration phase where a magneticfield is strong enough to damage the RFID/NFC (card/tag).

Next, the power receiver can perform the RFID/NFC detection operationusing the embedded NFC function during the re-ping time (S22040). Oncethe set re-ping time expires, the power transmitter and power receivercan perform the ping step.

Next, when the power receiver detects the RFID/NFC (card/tag), ittransmits an EPT packet (set to 0x0D) including the detection result(during the ping phase or at the start of the ping phase) to the powertransmitter, and thus allowing the power transmitter to remove theelectric power signal (or stop power transfer) (S22050). The powertransmitter receiving the EPT packet (set to 0x0D) may remove theelectric power signal (or stop power transfer). Furthermore, the powertransmitter can guide a user to remove the detected RFID/NFC (card/tag).

As shown in the flowchart, in order to determine whether the powertransmitter detects the RFID/NFC, the power receiver may transmit ageneral request packet requesting the capability packet, but it maytransmit a specific request packet having a newly defined request code,and thus it may confirm whether the power transmitter has detected theRFID/NFC. For example, the power receiver may transmit a specificrequest packet including a request field with a code/value of 0x05 tothe power transmitter, and thus may inquire to the power transmitterwhether the RFID/NFC has been detected.

The power transmitter receiving the specific request packet maytransmit:

-   -   ACK (or NACK (Negative Acknowledge)) response if has detected an        RFID/NFC (card/tag)    -   NACK (or ACK) response if it has detected the RFID/NFC        (card/tag)    -   ND (Not Defined) response if it has not known whether the        RFID/NFC (card/tag) exists or not (for example, if the power        transmitter does not understand a new request included in the        specific request packet), respectively.

The power receiver can determine whether the RFID/NFC is detected basedon the response sent from the power transmitter.

The power receiver may confirm whether the RFID/NFC has been detectedbased on a response transmitted from the power transmitter.

FIG. 23 illustrates a re-ping time packet format according to anembodiment of the present invention.

As described above, in order to perform the RFID/NFC detectionoperation, the power receiver may cause the power transmitter toimmediately stop transmitting power and perform the ping phase againafter the re-ping time defined in the re-ping time packet (i.e. returnto the ping phase). To this end, a new type of re-ping time packet maybe defined.

The re-ping time packet may have the bit size of 0x0A and may include are-ping time bit/field and/or an Immed bit/field. Here, the Immedbit/field may optionally be included in the re-ping time packetaccording to the embodiment.

The Re-ping time bit/field may be composed of 6 bits size and mayindicate Tre-ping as an unsigned integer value. Here, the Tre-pingcorresponds to the value of a re-ping time multiplied by 0.2 seconds.That is, the power transmitter may divide the Tre-ping obtained throughthe re-ping time bit/field by 0.2 and then obtain the re-ping time to beactually applied to. The range of the Tre-ping may be limited to between0.2 sec and 12.6 sec.

The Immed bit/field can be composed of 1-bit size, indicating the powerinterruption time of the power transmitter, and the contents indicatedby each bit/field value can be illustrated as follows.

-   -   1 (or ‘1’ b): immediately remove the electric power signal and        indicate to re-perform/regress the ping phase after the re-ping        time (or the Tre-ping time) (i.e., restart the WPC protocol).    -   0 (or ‘O’ b): Upon receiving an EPT packet (set to 0x0C or        indicating the re-ping) from the power receiver, it removes the        electric power signal and instructs to re-perform/regress the        ping phase after the re-ping time (or the Tre-ping time) (i.e.,        restart the WPC protocol).

FIG. 24 illustrates a configuration packet format according to anembodiment of the present invention.

Referring to FIG. 24, the configuration packet (0x51) includes variousconfiguration information related to the power reception of the powerreceiver. For example, the configuration packet may include a powerclass bit/field (2 bits), a maximum power value bit/field (6 bits), aProp bit/field (1 bit), a Count bit/field (5 bits), a window offsetbit/field (3 bits), a Neg bit/field (1 bit), a polarity bit/field (1bit), a Depth bit/field (2 bits) and/or an NFC bit/field (1 bit).

The power class bits/field indicates the power class of the wirelesspower transmission/reception system. This bit/field can be set to avalue of ‘00’ (indicating class 0).

The maximum power value bit/field may indicate different informationdepending on whether the power receiver supports the FOD extensionfunction. If the power receiver does not support the FOD extensionfunction, this bit/field may indicate the maximum amount of power thatthe power receiver expects to receive from the output of the powertransmitter/rectifier. If the power receiver supports the FOD extensionfunction, this bit/field may indicate the scaling factor of the receivedpower value reported as the received power packet by the power receiver.In this case, the power receiver may set this bit/field to a value twicethe maximum power (watt) that it expects to receive.

The Prop bit/field may indicate the power transmission control scheme ofthe power transmitter.

If the Neg bit/field is set to ‘0’, this may indicate that the powertransmitter does not transmit any response. If this bit/field is set to‘1’, this may indicate that the power transmitter should transmit an ACK(Acknowledge) response after the configuration packet indicating to thepower receiver that it will enter the negotiation phase.

If the polarity bit/field is set to ‘0’, this may indicate that thepower transmitter should use the default FSK polarity. If this bit/fieldis set to ‘1’, this may indicate that the power transmitter should usethe reversed FSK polarity.

The depth bit/field may indicate the FSK modulation depth.

The Count bit/field may indicate the number of optional configurationpackets transmitted by the power receiver in theidentification/configuration phase.

The window size bits/field can indicate the window size averaged thereception power in units of 4 ms.

The window offset bit/field may indicate the time interval between thewindow for averaging the reception power and transmission of thereception power packet in units of 4 ms.

The NFC bit/field may indicate whether the NFC has been detected by thepower receiver. For example, when this bit/field is set to ‘1’ b, itindicates that the NFC/RFID (card/tag) has been detected by the powerreceiver. Thus, the power transmitter receiving this bit/field shouldremove the electric power signal. On the other hand, when this bit/fieldis set to ‘O’ b, it indicates that the NFC/RFID (card/tag) has not beendetected by the power receiver. Thus, the power transmitter receivingthis bit/field may continue the WPC protocol without removing theelectric power signal.

The information indicated by each bit/field value is only an example,and the bit/field value indicating each information may be changedaccording to the embodiment.

FIG. 25 illustrates a specific request packet format according to anembodiment of the present invention. More specifically, FIG. 25 (a)illustrates a specific request packet format, and FIG. 25 (b)illustrates request field values included in the specific requestpacket.

Referring to FIG. 25 (a), a specific request packet (0x20) may mainlyinclude a request field and a request parameter field. The request fieldmay include information requested by the power receiver to the powertransmitter, and the request parameter field may include a parameter ofthe request.

Referring to FIG. 25 (b), the request fields 0x00 to 0x04 and 0xF0 to0xFF are set to indicate request information requesting for the powertransmitters, respectively, and at least one value of 0x05 to 0xEFremained as a reserved bit is set to power and may be used to indicatewhether the receiver has detected the RFID/NFC (card/tag). For example,the request field set to 0x05 indicates that the power receiver hasdetected the RFID/NFC (card/tag). Thus, the power transmitter receivingthis bit/field should remove the electric power signal.

FIG. 26 is a flowchart illustrating a power transfer method of a powertransmitter according to an embodiment of the present invention. Withrespect to this flow chart, the embodiments and descriptions of FIGS. 11to 25 described above can be applied in the same/similar manner, and theredundant description will be omitted.

First, the power transmitter may perform a selection step that monitorsthe placement and removal of an object to the interface surface of thepower transmitter (S2610).

Next, the power transmitter may perform a ping step of performingdigital ping and receiving a response from the power receiver (S2620).

Next, the power transmitter may receive the configuration packetincluding the configuration information of the power receiver (S2630).The configuration packet format may follow the embodiment of FIG. 24.

Next, a negotiation step of transmitting a capability packet includinginformation on a power level transmitted from the power transmitter maybe performed (S2640). The capability packet may be transmitted inresponse to a general request field transmitted from the power receiver.The capability packet may include an NFC detection field indicatingwhether the power transmitter has a capability of detecting the RFIDand/or the NFC, and/or whether the RFID and/or the NFC has beendetected. The NFC detection field includes a first subfield (e.g., NFCPPbit/field) indicating whether the power transmitter has a capability ofdetecting the RFID and/or the NFC and a second subfield (e.g., NFCDbit/field) indicating whether the RFID and/or the NFC is detected. Inaddition, various embodiments for the NFC detection field format are asdescribed above in FIG. 12-16.

If the NFC detection field indicates that the power transmitter has nocapability of detecting the RFID and/or the NFC, the power transmittermay receive a first EPT packet indicating a power transfer terminationfrom the power receiver (S2650). The first EPT packet may include afirst EPT code (e.g., 0x0C) requesting a removal of a power signal for apre-configured time. The power receiver may perform the detectionoperation for the RFID and/or the NFC during the pre-configured time,and the power transmitter may return to the ping step (S2620) afterremoving the power signal for a pre-configured time (S2660). The powersignal is removed for a pre-configured time because the electric powersignal transmitted by the power transmitter may act asinterference/disturbance with the detection operation by the RFID and/orthe NFC of the power receiver.

The pre-configured time may be indicated through a specific packet(e.g., a re-ping time packet) transmitted from the power receiver in thenegotiation step (S2640). The packet can indicate the predefined time inunits of 0.2 second. The packet may include an Immed (Immediate) fieldindicating the time at which the power transmitter removes the powersignal. The Immed field may instruct the power transmitter toimmediately remove the power signal or to remove the power signal whenthe power transmitter receives the first EPT packet. An embodiment forsuch a packet format is as described above in FIG. 23.

When the digital ping is performed according to the return to the pingstep (S2610), the power transmitter may receive the second EPT packetfrom the power receiver. In this case, the second EPT packet may includea second EPT code requesting a removal of the power signal as the RFIDand/or the NFC is detected by the power receiver for a pre-configuredtime. The power transmitter receiving the second EPT packet may removethe power signal and provide the RFID and/or the NFC detection resultsto a user.

Although not shown in this flow chart, if the NFC detection fieldindicates that the power transmitter has a capability of detecting theRFID and/or the NFC and the RFID and/or NFC is not detected, in order toimprove capability of detecting a foreign object during a power transferof the power transmitter, a calibration step may be performed to adjustspecific parameters.

Or, if the NFC detection field indicates that the power transmitter hasa capability of detecting the RFID and/or the NFC, and that the RFIDand/or the NFC is detected, it may not enter the calibration step. Inthis case, the power transmitter may remove the power signal and providethe RFID and/or the NFC detection results to a user.

Although the drawings have been described for the sake of convenience ofexplanation, it is also possible to design a new embodiment to beimplemented by merging the embodiments described in each drawing.Further, configurations and methods of the described embodiments may notbe limitedly applied to the aforementioned present invention, but all orsome of the respective embodiments may be selectively combined andconfigured so as to be variously modified.

Further, while the embodiments of the present invention have beenillustrated and described above, the present invention is not limited tothe aforementioned specific embodiments, various modifications may bemade by a person with ordinary skill in the technical field to which thepresent invention pertains without departing from the subject matters ofthe present invention that are claimed in the claims, and thesemodifications should not be appreciated individually from the technicalspirit or prospect of the present invention.

Meanwhile, in the present specification, A and/or B can be interpretedto mean at least one of A and B.

INDUSTRIAL APPLICABILITY

The present invention can be applied to various wireless chargingtechniques.

1. A method for transferring wireless power by a power transmitter, themethod comprises: a selection step of monitoring a placement or aremoval of an object on or from an interface surface of the powertransmitter; a ping step of performing a digital ping and receiving aresponse from a power receiver; an identifying/configuring step ofreceiving a configuration packet including configuration information ofthe power receiver; and a negotiating step of transmitting a capabilitypacket including information on a level of power transferred by thepower transmitter, wherein the capability packet may include an NFCdetection field indicating whether the power transmitter has acapability of detecting a Radio-Frequency Identification (RFID) and/or aNear Field Communication (NFC), and/or whether the RFID and/or the NFCis detected, and when the NFC detection field indicates that the powertransmitter does not have the capability of detecting the RFID and/orthe NFC: receiving a first End Power Transfer (EPT) packet forindicating a termination of a power transfer from the power receiver;wherein the first EPT packet includes a first EPT code requesting aremoval of a power signal for a pre-configured time, removing the powersignal for the pre-configured time, and returning to the ping step. 2.The method of claim 1, wherein the NFC detection field is divided into:a first subfield indicating whether the power transmitter has thecapability of detecting the RFID and/or the NFC, and a second subfieldindicating whether the RFID and/or the NFC is detected.
 3. The method ofclaim 2, further comprising a step of receiving a second EPT packet fromthe power receiver, when re-performing the digital ping according to thereturning to the ping step, wherein the second EPT packet includes asecond EPT code requesting the removal of the power signal as the RFIDand/or the NFC is detected by the power receiver for the pre-configuredtime.
 4. The method of claim 3, further comprising a step of: when thesecond EPT packet is received, removing the power signal, and providinga detection result of the RFID and/or the NFC to a user.
 5. The methodof claim 2, further comprising: a calibration step of adjusting aspecific parameter to improve the foreign object detection capabilityduring the power transfer of the power transmitter, when the NFCdetection field indicates that the power transmitter has the capabilityof detecting the RFID and/or the NFC, and the RFID and/or the NFC is notdetected, and a step of not entering the calibration step, when the NFCdetection field indicates that the power transmitter has the capabilityof detecting the RFID and/or the NFC, and the RFID and/or NFC isdetected.
 6. The method of claim 5, wherein the step of not entering thecalibration step further comprising the step of: removing the powersignal and providing a detection result of the RFID and/or the NFCdetection to a user.
 7. The method of claim 1, wherein thepre-configured time is indicated via a packet transmitted from the powerreceiver in the negotiating step.
 8. The method of claim 7, wherein thepacket includes a field indicating time at which the power transmitterremoves the power signal.
 9. The method of claim 8, wherein the fieldindicates the power transmitter to immediately remove the power signalor to remove the power signal when the power transmitter receives thefirst EPT packet.
 10. The method of claim 7, wherein the packetindicates the pre-configured time in units of 0.2 seconds.
 11. Themethod of claim 1, wherein the capability packet is transmitted as aresponse to a general request field transmitted from the power receiver.12. A power transmitter, comprising: a coil assembly comprising at leastone primary coil to generate a magnetic field; a power conversion unitconfigured to convert electric energy into a power signal; and acommunication and control unit configured to control a communicationwith a power receiver and a power transfer, wherein the communicationand control unit is further configured to: monitor a placement or aremoval of an object on or from an interface surface of the powertransmitter; perform a digital ping and receive a response from thepower receiver; receive a configuration packet including configurationinformation of the power receiver; and transmit a capability packetincluding information on a level of power transferred by the powertransmitter, wherein the capability packet includes an NFC detectionfield indicating whether the power transmitter has a capability ofdetecting a Radio-Frequency Identification (RFID) and/or a Near FieldCommunication (NFC), and/or whether the RFID and/or the NFC is detected,and when the NFC detection field indicates to the power transmitter thatthere is no ability to detect the RFID and/or the NFC: receive a firstEnd Power Transfer (EPT) packet for indicating a termination of thepower transfer from the power receiver; wherein the first EPT packetincludes a first EPT code requesting a removal of a power signal for apre-configured time, remove the power signal for the pre-configuredtime, and re-performing the digital ping.
 13. The power transmitter ofclaim 12, wherein the NFC detection field is divided into: a firstsubfield indicating whether the power transmitter has the capability ofdetecting the RFID and/or the NFC, and a second subfield indicatingwhether the RFID and/or the NFC is detected.
 14. A power receiver,comprising: a coil assembly including at least one secondary coil toreceive power; a power pick-up unit configured to convert a power signalreceived through the coil assembly into electric energy; an NFCfunctional unit configured to detect Radio Frequency Identification(RFID) and/or Near Field Communication (NFC); and a communication andcontrol unit configured to control a communication with the powertransmitter and a power transfer; wherein the communication and controlunit further configured to: transmit a response for a digital ping ofthe power transmitter; transmit a configuration packet includingconfiguration information of the power receiver; and receive acapability packet including information on a level of power transferredby the power transmitter, wherein the capability packet includes an NFCdetection field indicating whether the power transmitter has acapability of detecting a Radio-Frequency Identification (RFID) and/or aNear Field Communication (NFC), and/or whether the RFID and/or the NFCis detected, and when the NFC detection field indicates to the powertransmitter that there is no ability to detect the RFID and/or the NFC:transmit a first End Power Transfer (EPT) packet for indicating atermination of a power transfer from the power receiver; wherein thefirst EPT packet includes a first EPT code requesting a removal of apower signal for a pre-configured time, detect the RFID and/or the NFCusing the NFC functional unit for the pre-configured time.
 15. The powerreceiver of claim 14, wherein the NFC detection field is divided into: afirst subfield indicating whether the electric power transmitter has thecapability of detecting the RFID and/or the NFC, and a second subfieldindicating whether the RFID and/or the NFC is detected.